Prevalence of IgG and IgM to SARS-CoV-2 and other human coronaviruses in The Democratic Republic of Congo, Sierra Leone and Uganda: A Longitudinal Study

Abstract

Objectives We assessed the prevalence of immunoglobulin G (IgG) and immunoglobulin M (IgM) against four endemic human coronaviruses (HCoVs) and two SARS-CoV-2 antigens, among vaccinated and unvaccinated staff at health care centres in Uganda, Sierra Leone, and the Democratic Republic of Congo (DRC). Methods Government health facility staff who had patient contact in Goma (DRC), Kambia District (Sierra Leone), and Masaka District (Uganda) were enrolled. Questionnaires and blood samples were collected at three timepoints over four months. Blood samples were analysed with the Luminex MAGPIX. Results Among unvaccinated participants, the prevalence of IgG/IgM antibodies against SARS-CoV-2 RBD or N-protein at enrolment was 70% in Goma (138/196), 89% in Kambia (112/126) and 89% in Masaka (190/213). IgG responses against endemic HCoVs at baseline were not associated with SAR-CoV-2 sero-acquisition during follow-up. Among vaccinated participants, those who had evidence of SARS-CoV-2 IgG/IgM at baseline tended to have higher IgG responses to vaccination compared to those SARS-CoV-2 seronegative at baseline, controlling for the time of sample collection since vaccination. Conclusions The high levels of natural immunity and hybrid immunity should be incorporated into both vaccination policy and prediction models of the impact of subsequent waves of infection in these settings.

High pre‐Delta and early‐Omicron SARS‐CoV‐2 seroprevalence detected in dried blood samples from Kinshasa (D.R. Congo)

“…Within the 2021 blood donor cohort, seroprevalence reached 61%. This finding is slightly lower than others in the country which have reported up to 70% 13,14,48 and similar to surveys in Somalia, 18 Uganda, 19 Nigeria, 22 Burkina Faso 49 or South Africa 50,51 where antibody detection between 56% and 67% by 2021 has been reported. Although much lower seroprevalence has been estimated in studies in the Republic of the Congo (31.8%) 11 and Gabon (13%), 52 both relied on lateral‐flow rapid immunochromatography tests, which could justify the difference.…”

“…Cross‐reactivity of pre‐pandemic samples from African patients has raised concerns regarding the analytic performance of the commercially available testing platforms 14,28,63 . Our study shows over 90% global sensitivity in all assays except IgM+A detection.…”

“…In the DRC, only 99,338 cases have been declared since the start of the pandemic, which represent roughly 0.11% of its 92 million population. In contrast, studies in the DRC have found seroprevalences ranging from 48% 12 to 70% 13,14 . A similar phenomenon has occurred in neighboring countries such as Republic of the Congo, 15 Cameroon, 16 Gambia, 17 Somalia, 18 Uganda, 12,14,19 Tanzania, 20 Nigeria 12,21,22 and Kenya, 23–25 where growing evidence indicates pandemic burden has been grossly underestimated.…”

SARS‐CoV‐2 seroprevalence and associated factors among people living with HIV in Sierra Leone

“…One national survey in March 2021 reported an overall immunoglobulin G (IgG) antibody seroprevalence of 2.3% and immunoglobulin M (IgM) of 0.6% 14 . Another study between March and July 2021 reported an IgG/IgM antibodies seroprevalence of 89% among the unvaccinated health facility staff 15 . As of the time of writing, there are no reports on the seroprevalence of SARS‐CoV‐2 IgG/IgM antibodies in PLWH in Sierra Leone.…”